| Subject | Re: [PATCH 5.8 101/186] drm/radeon: Prefer lower feedback dividers | From | Christian König <> | Date | Wed, 9 Sep 2020 13:15:13 +0200 |
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Hi Greg,
please drop that patch. It turned out to break a lot of different setups and we are going to revert it now.
Thanks, Christian.
Am 08.09.20 um 17:24 schrieb Greg Kroah-Hartman: > From: Kai-Heng Feng <kai.heng.feng@canonical.com> > > [ Upstream commit fc8c70526bd30733ea8667adb8b8ffebea30a8ed ] > > Commit 2e26ccb119bd ("drm/radeon: prefer lower reference dividers") > fixed screen flicker for HP Compaq nx9420 but breaks other laptops like > Asus X50SL. > > Turns out we also need to favor lower feedback dividers. > > Users confirmed this change fixes the regression and doesn't regress the > original fix. > > Fixes: 2e26ccb119bd ("drm/radeon: prefer lower reference dividers") > BugLink: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbugs.launchpad.net%2Fbugs%2F1791312&data=02%7C01%7Cchristian.koenig%40amd.com%7C9fcd8f691f97451da30608d8540e3896%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637351767352887370&sdata=KKx0nGwITXVSg5Bg7XJHbVh0T30knZDioivKxO4%2F%2BB0%3D&reserved=0 > BugLink: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbugs.launchpad.net%2Fbugs%2F1861554&data=02%7C01%7Cchristian.koenig%40amd.com%7C9fcd8f691f97451da30608d8540e3896%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637351767352897339&sdata=KWknTc75Zjw3clREsEfY6wtDcv%2F3gddeyHhrhlHN0nY%3D&reserved=0 > Reviewed-by: Christian König <christian.koenig@amd.com> > Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com> > Signed-off-by: Alex Deucher <alexander.deucher@amd.com> > Signed-off-by: Sasha Levin <sashal@kernel.org> > --- > drivers/gpu/drm/radeon/radeon_display.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/radeon/radeon_display.c b/drivers/gpu/drm/radeon/radeon_display.c > index df1a7eb736517..840c4bf6307fd 100644 > --- a/drivers/gpu/drm/radeon/radeon_display.c > +++ b/drivers/gpu/drm/radeon/radeon_display.c > @@ -933,7 +933,7 @@ static void avivo_get_fb_ref_div(unsigned nom, unsigned den, unsigned post_div, > > /* get matching reference and feedback divider */ > *ref_div = min(max(den/post_div, 1u), ref_div_max); > - *fb_div = DIV_ROUND_CLOSEST(nom * *ref_div * post_div, den); > + *fb_div = max(nom * *ref_div * post_div / den, 1u); > > /* limit fb divider to its maximum */ > if (*fb_div > fb_div_max) {
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